diff --git a/.changeset/blue-bears-roll.md b/.changeset/blue-bears-roll.md
new file mode 100644
index 000000000000..e21b9642879b
--- /dev/null
+++ b/.changeset/blue-bears-roll.md
@@ -0,0 +1,5 @@
+---
+"@sveltejs/kit": patch
+---
+
+fix: add `null` to `RemoteFormInput` type to allow nullable schema validators
diff --git a/packages/kit/src/exports/public.d.ts b/packages/kit/src/exports/public.d.ts
index 1bae4ca70b47..1f05380a007c 100644
--- a/packages/kit/src/exports/public.d.ts
+++ b/packages/kit/src/exports/public.d.ts
@@ -2090,7 +2090,7 @@ type RecursiveFormFields = RemoteFormFieldContainer<any> & {
 type MaybeArray<T> = T | T[];
 
 export interface RemoteFormInput {
-	[key: string]: MaybeArray<string | number | boolean | File | RemoteFormInput>;
+	[key: string]: MaybeArray<string | number | boolean | File | null | undefined | RemoteFormInput>;
 }
 
 export interface RemoteFormIssue {
diff --git a/packages/kit/test/types/remote.test.ts b/packages/kit/test/types/remote.test.ts
index 2d00abec55af..30a89eb09bd5 100644
--- a/packages/kit/test/types/remote.test.ts
+++ b/packages/kit/test/types/remote.test.ts
@@ -624,6 +624,27 @@ function form_tests() {
 	f11_field2.propA;
 	// @ts-expect-error
 	f11_field2.propB;
+
+	// schema with nullable values (e.g. Zod nullable())
+	const f12 = form(
+		null as any as StandardSchemaV1<{
+			nullable_string: string | null;
+			nested: { nullable_value: number | null };
+		}>,
+		(data) => {
+			data.nullable_string === '' || data.nullable_string === null;
+			data.nested.nullable_value === 0 || data.nested.nullable_value === null;
+			// @ts-expect-error
+			data.nonexistent;
+			return { success: true };
+		}
+	);
+	// @ts-expect-error
+	f12.fields.as('text');
+	f12.fields.nullable_string.issues();
+	f12.fields.nullable_string.value();
+	f12.fields.nested.nullable_value.issues();
+	f12.fields.nested.nullable_value.value();
 }
 form_tests();
 
diff --git a/packages/kit/types/index.d.ts b/packages/kit/types/index.d.ts
index cf5f41397366..0188a2e81773 100644
--- a/packages/kit/types/index.d.ts
+++ b/packages/kit/types/index.d.ts
@@ -2064,7 +2064,7 @@ declare module '@sveltejs/kit' {
 	type MaybeArray<T> = T | T[];
 
 	export interface RemoteFormInput {
-		[key: string]: MaybeArray<string | number | boolean | File | RemoteFormInput>;
+		[key: string]: MaybeArray<string | number | boolean | File | null | undefined | RemoteFormInput>;
 	}
 
 	export interface RemoteFormIssue {